If the FAULT light on the IRS Mode Selector Unit illuminates; it indicates:
A.A.A failure of a Symbol Generator or a system fault affective NAV Mode of the ADIRU
B.B.An entry of an invalid present position
C.C.A system fault affecting the respective IRS ATT and/or NAV Mode
D.D.That DC power for the respective IRS is not normal
正确答案是C